


Under My Skin

by IdleSin (inkstainedwretch)



Series: Metal and Magic [7]
Category: Undertale (Video Game)
Genre: Cunnilingus, Interchangeable Robot Genitalia, Other, Reader has a vulva, Soul Sex, Strap-Ons, Vaginal Fingering, an astounding amount of plot, filthy sin and ridiculous fluff, gaster is not evil, with a side of overwrought melodrama
Language: English
Status: Completed
Published: 2016-01-21
Updated: 2016-01-21
Packaged: 2018-05-15 07:07:09
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 9,925
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5776222
Author URL: https://archiveofourown.org/users/inkstainedwretch/pseuds/IdleSin
Summary: <blockquote class="userstuff">
              <p>You've spent weeks now helping Undyne with her surprise for Alphys, as have Sans, Papyrus, and Mettaton. It's all about to pay off, if the Core temperature readings would just behave for five minutes. </p><p>(As it turns out, Mettaton's been working on a surprise for you, too - if he ever gets the chance to give it to you.)</p><p>[Reader has a vulva, but no gendered pronouns are used. There's also no specific chest stuff (mentions of bras, etc.), in case that's a concern of yours.]</p>
            </blockquote>





	Under My Skin

**Author's Note:**

> So, this is the end. (Of this series, anyway.) I start a new job next week, so I wanted to make sure this series was all wrapped up before I got too busy to write. Thanks to everyone who's been reading! I hope you all enjoy.
> 
> (Also: please don't ask me about how any of the magic works in this story, I'm just making things up. I probably got everything about Gaster wrong, despite my hours of reading and re-reading the Undertale wiki. I'm sorry, this idea just wouldn't leave my brain.)

"Darling, what on _earth_ are you doing?"

You turn to see Mettaton walking briskly towards you, licking a bit of spectral mustard off your lower lip.

"Napstablook brought some ghost food over to see if I can eat it with the wristbands on." you reply. "Turns out I can. It's not bad."

"Oh, r-really?" Napstablook looks away from you. "You don't have to be nice... I know it's not that great."

"No for real, this is pretty good," you take another bite of the sandwich. It tastes like you're eating clouds flavored like bread and cheese, but it dissolves on your tongue the same as any other monster food.

"When did you make a second set of- never mind," Mettaton shakes his head. "Undyne is _already on her way_ , so I suggest you get to your mark."

You look at the clock, and sure enough your spectral culinary endeavor has gone a full hour longer than you thought it would.

"Oh frick," you hop out of your chair. "Sorry about that. Hang tight, Blook. You're gonna want to see this."

"Okay..."

You check to make sure Alphys is still at her work table before shuffling over to the lighting controls by the far wall. You're pretty sure this is the only lab in the underground, if not planet Earth, that has a spotlight rig installed into the ceiling, but it worked for the quiz show and now it's gonna work for Undyne.

You hover your fingers over the controls, running through the rehearsals you've done in your mind. The controls are blessedly simple, and given the fact that you'd never worked a lighting rig in your life up to now, you think it'll go alright. The only part you actually worry about is Undyne getting here in the first place. Sans and Papyrus swore they could make it work, but they never explained to you how they planned on getting Undyne here in full armor without her overheating.

The clanking sound of royal guard armor echoes faintly from outside, and you watch Mettaton for a few moments until he gives you your cue. Your palm has been poised above the switches for every light in the room, and you slide it down firmly and plunge the room into darkness.

"Aah!" Alphys squeaks. "W-what's going on?"

You see the door to the lab slide open, Undyne's armored silhouette casting a shadow on the floor. You turn the spotlight on, and thankfully it's positioned right where you left it, so it throws its light straight at her. You can see steam curling up from under the plates of her armor, and you realize the skeleton brothers' cooling method must have been to stuff her armor with snow. It looks very dramatic.

Undyne removes her helmet, swishing her hair to the side, and the fan Mettaton has going makes it flutter. She's still wearing the makeup he applied for her this morning, and she looks...really cool. Her eyeliner has a point to it that looks outright deadly, and her lips glisten red. She looks straight at Alphys, who you can just barely see covering her mouth with both hands, and slowly makes her way toward her. You see Sans and Papyrus slip inside before the lab door closes, quietly high-fiving with a soft clack of bones. 

You follow her with the spotlight, ignoring your phone as it buzzes in your pocket. She reaches Alphys's work table and reclines onto one knee. Alphys is completely red, all the way down to her neck, and you can't help but grin. You hear Alphys's phone buzz loudly on her work table, but she doesn't even look at it. Undyne takes her hand and kisses it, and she squeals softly and begins to shake.

"Alphys," Undyne begins, her tone exactly as suave and heartfelt as Mettaton had instructed, "I've been so-"

She's cut off by the sound of Napstablook's cell phone, which they apparently forgot to put on silent. You wheel around to look at them with stunned eyes; you honestly didn't even know they _had_ a cell phone.

"Oh no..." they fidget, "sorry...huh. I didn't know Temmie had my number..."

"Wait, Temmie? Which Temmie?" Alphys asks, looking concerned.

"The one that...w-works here..."

You pull your phone out of your pocket and see a missed call from Temmie (Lab Assistant).

"She tried to call me, too... "Alphys says, looking at her own phone screen.

You wonder why Temmie would be calling any of you, but then it hits you that she's been at the Core all day...

"Answer it," you tell Napstablook, ignoring the fact that Undyne looks incredibly confused and Mettaton looks absolutely _livid_.

"O-Okay..." they answer the call. "Hello...?"

"hOI!!!!!!!!!" Temmie's voice is loud enough for you to hear it. "tem hav URGENT MESSEGE!!"

"Put her on speaker," Alphys says, jumping out of her chair and running over to Napstablook. You switch the lights on and follow her, hoping to god this isn't what you think it is.

Napstablook looks a little panicked, but they push the speaker button nonetheless.

"Temmie?" Alphys asks. "It's Alphys. Are you okay?"

"yaYA!" Temmie says. "but core NOT OK! going CRAZYPANTS! GONNA SPLODE!"

"How hot?" you ask, feeling dread start to well up in your stomach. "Is it doing the rapid fluctuation like we saw a couple of weeks ago?"

"NO!!!!!!!!!!!!" Temmie shouts. "moving WAY FASTER! BOING BOING!!!"

"Holy shit," Alphys brings her hands up to her face. "Are you okay? Are you safe?"

"I'm fine," Temmie's voice sounds unexpectedly grave, "but the building scanners won't let me start the lockdown. They keep saying someone's still inside."

"...oh god," Alphys takes off for the elevator. "I'll be right there, Temmie!"

You run after her, ignoring the shrill "WHAT THE **FUCK** " you hear behind you. The elevator doesn't move nearly fast enough, and you're so nervous your hands start to shake. 

"You don't think..." you look over at Alphys. "I mean, I know you stopped sending ice down the river-"

"Yeah, because we don't _need_ to anymore," Alphys shakes her head. "The barrier didn't just cover the exit to the surface, it sealed the whole underground from the Ruins on up. The only point heat ever escaped was Mt. Ebott, which is too far away to vent anything from the Core. With the barrier down, the heat should disperse just fine - and it _has been!_ Even then, overheating would be a lot easier to fix. This rapid shifting up and down...it doesn't make any sense."

"Asgore was saying this happens sometimes?"

"It does, but Temmie's seen the temperature readings from the last time it did this. She wouldn't have called unless it was acting even weirder. She definitely wouldn't have evacuated if the readings were in the same range."

"And the building scanners are saying someone's still inside..." you scratch your head. "How do they even know?"

"Magical signatures," the elevator door opens, and Alphys heads across the bridge. "They were only designed to detect monsters."

Temmie is outside the door to the Core, shaking so fast her face looks like it might detach completely from her body.

"Okay," Alphys looks at the screen on the outside of the building, scrolling through the scanner results. "Let's see where this person is..."

"asdfkljdasfgklfjgkldfsgjdsfklgjasdklfkjl" Temmie's eyes are wide and worried.

"What the _hell_..." Alphys taps the screen. "The scanner must be malfunctioning."

"What do you mean?" you look over her shoulder at the screen. It displays an error message that reads, _ERR: LOCKDOWN ABORTED. MAGICAL SIGNATURE PRESENT IN ROOM 269._ "Where's room 269?"

" _There is no room 269_ ," Alphys hisses frustratedly. "Let's see if I can pull it up on the map..."

She inputs the code to display the building map, and a bright green spot is blinking...five feet outside the walkway.

"Okay, that's _definitely_ wrong," you mutter. "Unless somebody walked straight into the Core. But nobody could've survived that, right?"

Alphys claps her hands over her mouth.

"What...?" you ask, but instead of answering she takes off again, heading straight down the hall faster than you've ever seen her run.

You follow her again, down the empty walkways, and as you near the spot that the map had identified, the air shimmers and shifts around you. In less than a second, you're no longer in the Core, but in a plain white hallway. You stop so fast you skid on the tile and fall, and the thud as you hit the ground doesn't echo. You can't see anything ahead of you or behind you, just darkness. The only thing in the hallway besides you is a plain grey door. Alphys is nowhere to be found.

"What," you say again, looking rapidly around you. "What. What? _What?_ "

You feel yourself begin to panic. The darkness of the hall around you almost looks like it's starting to creep inward. You wonder where you'd end up, if you walked into it.

Maybe it's better if you take your chances with the door.

The room inside is the same plain white, and it's nearly empty. The only thing inside is...a monster? A white-faced figure cloaked in black stands in the middle of the room, still and silent. Two black marks stretch from the top of one eye and the bottom of the other. Its mouth is...crooked. Its hands look like they might have been skeletal once, but they bear two enormous holes in the middle of  the palms. Its body looks almost fluid, and it shifts subtly, swirls of violet magic occasionally sparking through it.

You approach it slowly, expecting the floor to give out under you any minute, but it stays solid under your feet. The figure is facing down, its eye sockets empty. You wonder if it's even alive. Even though his face doesn't appear to be capable of much movement, you'd swear it looks almost sad. So despite the circumstances, the first thing out of your mouth is:

"Are you okay?"

With a shifting of black, its face turns up toward you. Small sparks of violet appear in its eye sockets, and its hands begin to move. Though its movement is slow, you recognize the sign language it uses.

_I do not recognize you._

"Uh..." you take a step back, unsure of what to say. You're not even sure the figure can hear you, so you start to sign instead, starting with your name. _I work with the Royal Scientist. Are you ok?_

They shiver and spark, their eyes flaring bright.

_I never worked with a human. Who is the Royal Scientist now?_

You raise an eyebrow, but spell out Alphys's name nonetheless. They seem to calm down a little.

_I see. We are much later. If a human works for us, the barrier must be down._

You nod again, wondering how this person knows so much about your job. Against all odds, your phone starts to buzz in your pocket. You didn't think you'd get any reception in whatever weird dimension you walked into. You answer it without looking to see who it is, hoping if you can talk to _anyone_ it will give you a shot at getting out of here.

"Hello?"

"Darling, where are you?" He sounds worried sick. "Alphys left her phone on her desk, and we can't reach her. Is everything alright?"

"Uh..." you look around you, wondering exactly how best to answer that. "I kind of...don't know where I am. Something weird happened at the Core, and now I'm in this weird white room?"

" _What?!_ " Mettaton shouts. "Oh my god, are you hurt? What happened?"

"I don't know," you say, and no matter how much you look the walls don't provide an answer. "Alphys didn't end up in here. It's just me and..."  You look back over at the shifting black figure, who seems to be listening to your conversation, despite the fact that you're not sure they can hear.

 _Who are you?_ You sign, wedging your phone between your ear and shoulder.

_I am no longer certain. Before, I was called Gaster._

"The only other person here says their name is Gaster?"

"Gaster?" Mettaton sounds very confused. "Never heard that name before. Do you think- _hey!_ "

There's the sound of a brief scuffle, and then someone else grabs Mettaton's phone.

" **where are you** ," Sans all but yells.

You nearly drop your phone, and the first time you bring it back up to your ear it's upside down.

"I don't _know_ ," you sigh in frustration. "We were in the Core, and something just _shifted_ , and...maybe this is room 269?"

"you're in the core? is gaster there with you?"

"Yeah," you nod, despite knowing he can't see it. "Yeah it's just me and Gaster. I don't know where Alphys went."

" **s t a y .  t h e r e .** "

"...okay." You feel a deep chill run down your back. You've never heard Sans talk like that before.

"if you leave, we'll lose him again. be there in a second," Sans hangs up.

_That sounded like Sans._

Your eyes go wide. How the hell would he know Sans?

Before you can answer, your phone buzzes again, this time with a text message. It's from Frisk of all people, and it looks like it was typed in a hurry. Two more messages pop up quickly on your screen, like Frisk can't send them fast enough.

[sans said you found him]

[is he ok]

[tell him I'm sorry]

You look back up at Gaster, wondering just how many people knew about him this whole time. _That was Sans. He's on his way._ _...Frisk says they are sorry._

Gaster tilts his head a little. _Who is Frisk?_

You flip through your phone until you find a picture of them, hanging from one of Papyrus's arms and grinning. You show him, and a spark of realization crosses his eyes.

_The other human. They are still alive._

You nod. _They brought the barrier down._

_They said they would return for me, but our paths have not crossed since._

_Come back for you?_ You raise an eyebrow. _Can you not leave?_

Gaster looks down slowly. He moves a little to the side, but the black substance that covers his body (or _is_ his body) remains tethered to the floor, stretching unpleasantly. He says something, but you don't understand it. It sounds _different_ , like the words should make sense but the letters have been all jumbled up and replaced with meaningless sounds. It sort of reminds you of the first time you heard Sans and Papyrus talk, hearing that subtle difference in the tone and structure of their words, but intensified so much you can't understand any of it.

"Um..." you say softly, not sure he could see you if you signed. "I didn't...get that."

Gaster begins to sign, but he doesn't look up. It seems he can hear you after all.

_I apologize. At times I forget. I am bound to this room. I am unbound from time. When Frisk found me, this room was in Waterfall._

"It moves around?"

_It does. I cannot control it. When they left, it was no longer there. Entering this room requires stabilizing energy. When that energy leaves, the room becomes unbound._

"What do you mean, unbound?" You scratch your head a little. This is starting to weird you out. Your phone buzzes again, and Frisk has sent you another text.

[tell him I'm coming back]

You smile just a little, then text them back. [I will. He remembers you.]

"Frisk is on the way too," you tell him, and his eyes flash again.

_Good. Perhaps with two humans, it will be more stable._

"Why humans?" you ask.

_Without a human present in this room, monsters cannot enter. Keeping it stable requires DETERMINATION._

" _There_ you are!"

With a relieved sigh, Mettaton runs full-tilt into the room and yanks you into his arms. You can hear his cooling fans working overtime, and his body is warmer than you've ever felt it. You smile and rub one hand over his back reassuringly, feeling so, so glad to have him here.

"I'm okay," you say softly.

"Thank god," he whispers breathlessly. "I don't know what the hell any of this is, but I'm getting you out of it safely if it's the last thing I do."

"Thank you," you peck him on the lips and turn around. "In the meantime, this is Gaster. Gaster, this is Mettaton."

Gaster gives him a polite wave, then turns his attention to the open door. There's the sound of skittering footsteps, and you wheel around to see Sans tumbling into the hall.

"I'm kinda surprised it took you this long," you say. "Are your shortcuts not working?"

"can't risk throwing off the energy field," he shakes his head. "too much going on already to jump from one field to another. might destabilize it."

"I frickin' knew it," you mutter. You could've written a whole new thesis on all the theories you've had about his shortcuts.

"oh my god," Sans falls to his knees in front of Gaster, looking absolutely astonished. "oh my god, it's really you."

You hear another clomping set of footsteps, and Papyrus comes barreling in after him.

"SANS SINCE WHEN DO YOU RUN THAT FAST- OH MY GOD."

Gaster says something again, and you still can't undertstand a word of it, but Sans and Papyrus seem to get it.

"yeah," Sans nods, his eye beginning to glow just a little bit green, "it's been a while, huh?"

"I DON'T UNDERSTAND," Papyrus walks slowly into the room. "I THOUGHT YOU WERE DEAD."

Gaster begins to speak again, and you sort of just look at your shoes. You don't understand what he's saying, but this feels like sort of a big moment that you don't want to interrupt. He gesticulates with his hands, and you can see the skeletal joints in his fingers as they move. If he's a skeleton too...or part skeleton, or he _used_ to be a skeleton, maybe they're related? You honestly have no idea. More than that, though, you feel like the only one who _doesn't_ understand what's going on.

Until Mettaton leans over your shoulder and mutters into your ear, anyway.

"Am I the only one who doesn't understand what he's saying?" he asks.

"Nope," you shake your head. "We've been signing."

Gaster starts a bit, then looks somewhat embarrassed. He begins to sign again.

_I apologize. I was explaining that falling into the Core has destabilized my being from time and space. I am no longer corporeal, no longer able to remain in any one timeline. This space I inhabit only manifests once in a great while. Without DETERMINATION, it does not remain still for long._

"so how do we get you out of here?" Sans asks.

_You cannot._

"WHAT?" Papyrus looks like he might cry. "WE HAVE TO GET YOU OUT OF HERE! WE HAVE TO BRING YOU BACK HOME!"

"Wait," Mettaton holds up a hand. "Can _we_ leave this place?"

 _Yes_.

"That settles that, then," Mettaton takes your hand. "Let's get you somewhere safe and see if Alphys knows any way to help him."

"I can't do that," you shake your head. "If I leave, the Determination leaves the room, and...it'll vanish again. Like it did when Frisk left."

"...Determination," Mettaton sighs softly. "Of course."

"I don't understand it either," you admit. "Determination is one of those things I could study forever and not completely get. But even if we can't help him, we have to at least try."

Mettaton is quiet for a long moment, and you worry for a second that he's going to try to make you leave. Honestly, you wouldn't blame him. Given how far into the room you walked, if the room vanished suddenly, you'd all fall into the Core. You've sort of been worried that it would do just that since you first got here. Eventually, he  looks right into your eyes, and even though he looks a little sad, he's smiling.

"Alright," he says softly. "As long as you stay here, so do I."

You blush deeply, feeling Sans's eyes burning a hole in your back.

"WHY CAN'T YOU LEAVE?" Papyrus asks. "CAN YOU EVEN MOVE?"

Gaster moves back a bit, showing them how his body stretches.

_My body and my soul are tethered to this shifting space. The ties cannot be broken by any external energy._

"NO..." you've never heard Papyrus so quiet. "NO, THERE HAS TO BE A WAY..."

Soft, slow footsteps tap against the floor out in the hall. Frisk reaches the doorway with hesitant, careful footsteps, but when they look through the doorway, they launch themselves inside and all but fall to the floor beside Sans. Their whole body shakes with tears, and they don't even look at Gaster as they sign frantically to him.

_I'm sorry I'm sorry I'm sorry I'm sorry_

Gaster regards them for a moment, the light in his eyes fading, and then his hands begin to move.

_You have grown. It has been some time._

Frisk dries their eyes on their sleeve, then nods.

_Years and years. I'm so sorry. I tried to find you again. I told Sans where you were. We looked and looked._

"hey," Sans puts a gentle hand on their shoulder. "it's okay kiddo. we're gonna get him out of here."

Gaster looks down again dejectedly.

_I am so thankful I could see you again, but you cannot move me. I can never leave._

Frisk huffs in frustration and reaches for Gaster, but their hand phases straight through his body. They fall to the floor with a surprised gasp, trembling from the shock. You look down at your own hands and get an idea.

"Can I...try something?" you ask, holding up your hands.

"Darling, you're _not_..." Mettaton's eyebrows begin to lift.

"I mean, it's worth a shot right?" You shrug. "Can I try touching you, Gaster?"

_I do not see how it would make a difference, but you may._

"Thanks."

You reach a hand out and slowly bring it down to one of his hands. You panic for a moment when your finger slips through, but then you realize your fingertips landed in the holes in his palm. The rest of your hand makes contact, and it's so _hot_ , hotter than that one time you accidentally touched a steam vent with your bare hand, but it doesn't burn.

He wraps his fingers around your palm, and you feel his hand start to shake.

"give me those," Sans reaches out to you. "i have an idea."

You let go of Gaster and take off the armbands, handing them to Sans. They're too big for his bony wrists, so he stretches them over the bones of his palms. He brings up an attack bone and touches it to the floor, right where Gaster's body sticks to it. It sparks, shrinks away, but then returns. Sans huffs in frustration. Gaster says something to him, and even though he doesn't sign it, you can tell he sounds frustrated.

"well if external magic won't work..." Sans looks up at him. "maybe something else will."

He turns to look at you and Frisk, and his eye glows bright blue.

"you're gonna want to get back," he says, "like back against the wall."

"SANS?" Papyrus looks at him with confusion. "WHAT ARE YOU DOING?"

"gonna show you a trick gaster taught me," Sans says, stepping back and squaring his shoulders. "you should probably go back there, too."

Papyrus walks toward the back wall, and the rest of you follow suit. You don't have the first clue what Sans is doing, but you've never seen his eye go that bright before, and Frisk looks a little bit scared. Mettaton's arms wrap around you, your back pressed snug against his chest.

Sans says something to Gaster in the same unreadable language he spoke in earlier, and Gaster begins to move back. Slowly, he makes his way back to the far wall, and as the black substance stretches thin you can see the outline of legs underneath it. When he's gone as far back as he can go, and the black starts to roll back towards him, Sans raises a hand.

An enormous monster skull materializes above him, with wide eyes and sideways jaws like a Gyftrot. Mettaton gasps and turns you both so you're facing the wall behind him. Papyrus scoops Frisk up into his arms and does the same thing. You turn around, looking in the small space between their arms so you can see what happens.

Sans lowers his hand, and the skull's mouth opens, sending a tremendous blast of white light down toward the spot where Gaster sticks to the floor. The noise it makes is so loud, you can't hear most of what Sans says afterwards. You blink spots out of your eyes until you can see Gaster crumpled against the far wall. There's a black scorch mark on the floor where the blast hit, but he doesn't appear to still be stuck there.

Papyrus sets Frisk down and runs straight to him, and when he reaches out to help him sit up, his hands don't phase through him. The liquid black surrounding his body starts to shrink, and it almost looks like it's being absorbed back into him.

"GASTER...?" Papyrus asks softly, putting a hand on his shoulder. "ARE YOU OKAY?"

Gaster says nothing for a long moment, and for a second you're honestly convinced Sans just accidentally killed him. That's when you see a set of translucent, faintly glowing hands materialize in front of him. A second pair follows, and then a third, and then a fourth. Two of them float to Frisk, clasping hands with them lightly. Another comes to pat you lightly on the shoulder, another to shake Sans's hand soundly, and Papyrus laughs as two of them rub the top of his skull affectionately. As he stands up, the final pair begins to sign.

_I have not been able to do this for so long. Thank you._

The hand that was on your shoulder offers itself to Mettaton, who shakes it politely. They all return to Gaster, and suddenly you remember something the River Person once said to you, about the man who speaks in hands.

"Wow," you laugh softly. "I think I'm the only person in the underground who didn't know who you were."

"No dear, you're really not," Mettaton sighs. "Now, then. Shall we? Not to sound impatient, but we were sort of in the middle of a perfectly choreographed production. ...and you probably need to see some kind of doctor."

You give his hand a squeeze in thanks. When Mettaton's out of his depth, he tends to try and shift focus back to himself, and you're pretty sure this qualifies as "out of his depth".

Gaster lets Papyrus help him out of the room, and you wait for everyone to leave, even Mettaton, before heading out of the room yourself. When you enter the darkness surrounding the hallway, the air shifts again, and you're back in the Core. The temperature alarms have stopped. You wonder if they've stopped for good.

"Hey!"

You turn around to see Alphys, looking abjectly terrified.

"Oh my g-god! What the hell was that?! I couldn't move for like half an hour! There was just this invisible _wall!_ "

"Huh," you raise an eyebrow. "Guess you could only get there from one side."

"And the Core temperatures went BALLISTIC! I thought it was gonna have a meltdown! How did any of you even get h-" she finally notices Gaster. "...is that...who are you?"

"someone who _really_ needs to be in a hospital bed right now," Sans urges you forward. "we can explain later."

You get Gaster into one of the beds in the lab, and before too long you've got all kinds of monitors and sensors surrounding him. One of the bendy amalgamates brings him some soup from the kitchen, which he drinks happily. Sans and Papyrus seem reluctant to leave his side, even after it's clear he'll be alright.

 _Thank you._ He says, leaning back against the raised head of the bed. _Never once did I dream this was possible. I may need time to recover. The years I have lost appear to be catching up to me._

"you'll be okay," Sans says, and it seems like it's more to reassure himself than to reassure Gaster. "you'll be okay. oh, here."

He takes the silver bands off of his hands and gives them back to you.

"Thanks," you slide them back on, feeling a faint tingle of magic left over from him.

"And who knows," Alphys fiddles with a knob on one of the sensor displays. "Maybe you c-can come back to the lab once you feel better."

 _That sounds very nice._ Gaster's eyes glow softly.

Behind you, one of the doors crashes open.

"NGAAAAAAAAH!" Undyne storms in, all her armor removed, Mettaton chasing frantically after her.

"Darling, no! You're not following the script!"

"SCREW your script!" She shouts. "I'M NOT WASTING ANY MORE TIME!!!"

She walks straight over to Alphys and puts her hands on her shoulders, her face flushed just a little. The room gets unbelievably quiet.

"Alphys..." she starts, sounding suddenly hesitant.

"Y-yeah?" Alphys says.

"...will you marry me?"

Alphys turns bright, bright red, her voice shrinking down to a squeak.

"...y-y-yes."

"FUCK YEAH!" Undyne punches the air in victory and wraps her arms around Alphys, kissing her hard enough to make her bend backward a little.

"...well, perhaps improvisation has its merits." Mettaton sighs heavily.

You laugh aloud and walk over to him, brushing your hand softly over his hair.

"Mettaton?" you ask.

"Yes, darling?"

"Why don't we go home?"

"That sounds like a marvelous idea."

The two of you say your goodbyes and head into the front hall, where Napstablook is still waiting exactly where you left them.

"Oh..." they say softly. "You're okay...that's good."

"We're all okay, Blooky," Mettaton smiles gently at them. "You can go home now, if you like."

"I h-heard you found somebody...are they okay too?"

"They'll be alright," you nod. "We wouldn't have found them at all if your phone hadn't been on, Blook. So, thanks."

"You...you c-can call me Blooky if you want...to..." they look down at the floor, shimmers of blue glowing over their face. "I wouldn't mind..."

You bring both hands up to your mouth and smile so hard it actually hurts. This might have just turned into the best day of your life.

"Then thank you, Blooky," you press a soft kiss to the top of their head, and they gasp.

"I-I-I had a question for doctor A-Alphys," they zoom off to the back of the lab. "I'll see you l-later..."

When you look back at Mettaton, he's laughing. You just whap him lightly on the shoulder, and together you make your way up to the resort.

The walk is quiet, although he does wrap one arm around your waist when you leave the lab. By the time you reach his suite, he hasn't let go even for a moment. As the elevator doors close behind you, he wraps his other arm around you and pulls you close. He holds you like that for a long time, and even though he doesn't say anything, you think you know why.

"I'm right here," you whisper. "I'm not going anywhere."

"I know," he says. "It's just...until today, I never seriously thought about what I would do if I lost you."

"I'm sorry..."

"Don't apologize," he shakes his head. "All you wanted to do was help."

He leans back and cups your face in both of his hands.

"You have such kindness," he whispers, "and patience, and integrity, and generosity, and..."

He kisses you softly, and you feel his warmth all the way down in your heart. The afternoon felt like some strange, fragmented dream, and only now does the weight of what just happened finally settle on you. Even when you were afraid of the floor giving out from under you, it didn't feel like you were in danger of actually dying. But if what happened to Gaster is any indication, you could have been risking a fate worse than death. Mettaton pulls away, his eyes shining, and you never want to let him go.

"I love you so much," he murmurs.

"I love you too," you rest your head on his shoulder and try to get a grip on the emotions welling up in your chest. Things you've tried so hard not to think about start to burst up from the ground. "I never thought...if something like that had happened to me when I lived on the surface...I don't think anyone would have come looking for me."

"Don't think about that right now," Mettaton's hand runs softly through your hair. "Right now, you have me. And you have Alphys and Blooky and those ridiculous skeletons and Undyne and Frisk and even the king and queen, and we all care about you, and we all want to keep you safe."

"M-hm," you blink a few times, your voice feeling sort of stuck. "I don't know what to feel...I'm so happy, but I'm so scared."

"Scared of what?" he asks. "From what I understand, Gaster was an isolated case."

"Not that," you shake your head. "I just didn't think I could be this happy."

"Oh darling," he smiles down at you. "What was it you told me...? You deserve to be happy, and you deserve to be loved."

"I guess..." you laugh, sounding just a little choked. "I guess I should take my own advice."

Mettaton presses a soft kiss to your forehead and leads you back to the chaise, lying down on his back and guiding you so you can lie on top of him. You stay like that for a while, listening to the gentle hum of his fans and processors and enjoying the feeling of his arms wrapped around you. You don't say much, though now and then one of you will tilt the other's chin towards you for a kiss. You simply enjoy being home, and being together, and being alive.

It may well be hours later when Mettaton's hand slides its way down your back, and he finally breaks the silence.

"Darling... I haven't just been working on a surprise for Alphys, you know."

He looks up at you with half-lidded eyes, his hand squeezing softly at your skin. You lift your head from his chest and raise a curious eyebrow.

"Is that so?"

"M-hmmmm~" one of his hands slides up to your neck, his fingertips barely brushing over your skin, "but I don't think I'm quite ready to show it to you."

"Oh?" You move your hand up the side of his heart container; two can play at this game. "When do you think you'll be ready to show me?"

"I haven't decided yet," he bends one knee, pressing just enough between your legs for you to notice.

"What's that supposed to mean?" you push your hips against him, answering the challenge.

"Well," his fingers flick over the top of your waistband, "it's going to take either one round or two."

"Then I guess we'd better get started," you work a hand into his hair and kiss him, feeling his hands already starting to undress you.

He sits you both up, letting you stand so he can get you out of your pants and underwear, and then he pulls you down onto his lap and makes quick work of your shirt. Both arms wind up your back, and his mouth is all over your neck, kissing frantically over your shoulders and as far up as your jawline. His hands don't stay still either, sliding slowly down your back, up your sides and over your legs, taking hold of you by the hips and keeping you close. You bite your lip and whimper softly, getting one hand back in his hair. With the other, you hesitantly reach for his heart container, watching the fluid begin to drip from his heart.

"We can see to me later, gorgeous," he purrs. "Right now, this is all about you."

One of his hands moves inward, and your hips jerk forward involuntarily, trying to meet it. He doesn't bother teasing you, spreading your lips apart with his fingers before sliding them inside. You tug at his hair and groan, rocking your hips with him as his fingers curl inside you. He bites gently at the side of your neck, then a little less gently, and his tongue laves over the marks left by his hard enamel teeth. His thumb moves up to your clit, vibrating slowly at first but rapidly gaining strength.

"Oh fuck," you whisper, grabbing at his hair as you feel heat build up inside you. " _Harder_."

"Of course, darling," his hand begins to move with purpose, pressing hard against your front walls.

You feel your eyes start to slip shut, and your breathing becomes rapid and shallow as bolts of pleasure start to spark their way up your body. Mettaton's mouth begins to move down your chest, hot and wet against your skin.

"Yes," you pant, grabbing his shoulder so hard your knuckles turn white. "Fuck yes, Mettaton, Metta- _ah_!"

"That's it," he murmurs, "that's it darling, let me watch you."

Your eyes squeeze shut and you scream, your walls clenching around his fingers as pleasure pulses inside you like an electric shock. Your hips shake and spasm on top of him, and he doesn't still his hand for a moment until you fall forward, desperately trying to catch your breath. You rest your head on his shoulder again and take a moment to breathe. When your eyes open again, you sit back up and look down at his heart container, now halfway filled.

"My my," you look back up at him and very pointedly lick your lips.

"Have something in mind?" he asks, leaning back a little.

"You could say that," you slide off of his lap and lower yourself slowly to the floor, reaching for the switch on his hip.

When the plates slide open, you're greeted with the sight of pink starting to drip from his inner lips. You drag your tongue over his folds, the sweetness flowing into your mouth, and you can't help but moan softly at the taste of it. Your tongue flicks up the underside of his clit, which gets you a surprised gasp and a hand on the back of your head. You look up at him with mischief in your eyes, repeating the motion once, then twice.

"Da-a- _aaarling,_ " he pants, "after a performance like that, you can't just t-t-ttttease me this way..."

"I beg to differ," you whisper, your lips barely grazing against him, and he's physically strong enough to hold your head down, but he doesn't. He won't.

Instead, what he does is toss his head to one side and bite his lip, looking down at you with pleading eyes. His pupils are flickering, and even though he doesn't really need to breathe, you can hear the hiss of it between his teeth.

God, he's pretty like this.

You decide to be generous and bring your mouth back down to his clit, mostly so he doesn't see your hand move up. Your first finger slides into him, and his surprised cry turns into static when you add a second. Pink drips from your mouth as your tongue circles his clit, and you feel his fingers grip your hair - but he doesn't pull any harder than you can handle. Even if he doesn't act like it, he's so considerate. Honestly, you're the luckiest person alive.

The way his legs begin to shake tells you he's already close (thanks in no small part to watching you; dating Mettaton might be the best thing that ever happened to your self-confidence). In the back of your head you remember what he said about wanting to show you something, so rather than tease him again you wrap your lips around his clit and suck gently.

"Ha _-aaah!_ " His eyes begin to close. "Mmmm, _yes_... Yes, just like that gorgeous..."

He bites the corner of his lip, but you can see that he's smiling. You move your hand faster and watch him, keeping your tongue moving until you feel him clench around your fingers. He's remarkably quiet, even though he still pants and cries out above you, vocals juddering and uneven. For Mettaton, the whole thing seems almost gentle. He leans his head back and hums happily, looking so...relaxed. It's new, but it's sweet, and somehow it makes you feel a little closer to him.

You rest your head on his thigh and sigh contentedly. There are some days where you wonder how in the world you and Mettaton, star of the underground, attention seeker and drama bomb extraordinaire, could ever be together. In the beginning, you swore he'd get bored of you after a week or two. Right now, though, it feels right. It feels like it could last.

Mettaton slowly lifts his head up and looks down at you, and his eyes are wonderfully soft.

"Are you happy, darling?" he asks.

"Very," you reply, pressing a soft kiss to his thigh. Your lips leave a pink mark on the shiny black surface.

"Good."

He smooths your hair down where his fingers have mussed it up, his motions slow and tender. In the very back of your mind, you realize he only asks you that when he knows the answer is "yes". You feel a bright warmth in your heart; if you could see your soul, you're sure it would be glowing.

He beckons you back up onto his lap, and once you're seated again he kisses you languidly. He tastes himself on your skin, sucking your lower lip between his teeth.

"I think I'm nearly ready," he murmurs. "Tell me what you want, dearest."

"I want to fuck you," you reply without hesitation.

"God yes," he sighs against your mouth. "Let me help you put it on?"

You nod and step off his lap, and the two of you make your way to the bed. He takes the toy and its accompanying harness out of the nightstand drawer, securing it around your hips with almost reverent hands. When it's on, you sit on the edge of the bed and scoot back, Mettaton following with a hungry look in his eye.

"Forgive me for delaying things, gorgeous," he says, rolling you onto your back and licking his lips. "I'm afraid I just can't resist~"

You're about to ask what the hell he's on about, but then he moves back onto his knees and bends forward, taking the shaft of your silicone cock into his hand and pressing a kiss to its tip. He winds his tongue around it in slow circles before sliding down, and the movement makes the base of the toy press up against you. Your face gets incredibly hot; you hadn't suggested this up until now because the idea seemed kind of dumb, but Mettaton seems more than enthusiastic about it.

"Whoa..." you say, a little shakily. "I didn't think you'd want to..."

Mettaton lifts his head back up, his lips making a soft pop when the shaft leaves his mouth.

"Why not?" He asks, continuing to work his hand around the base. The movement creates a delightful friction, and thankfully he waits for you to open your eyes again before speaking again. "You may not have a switch on your hip like I do, but this is still part of your body."

He flicks his tongue over the head, the motion reminiscent of what you did to him just minutes ago, and his eyebrow twitches upward.

"At least, I think so."

He takes you back into his mouth and starts to bob his head, looking up at you with the eye not covered by his hair. You never thought you'd enjoy this as much as you are; the design of the toy makes it very sensitive to movement. He makes it a hell of a show, too, dragging his tongue up the shaft before wrapping his lips back around you. After a bit, your hips start to jerk upwards, and a low whine escapes your lips.

"Agreed," Mettaton pants softly.

He sits back up and moves forward so he can straddle your hips, taking the base of your shaft in one hand and guiding it into him. You can feel the wet warmth begin to drip onto you as he slides down, and you instinctively take hold of his hips when he settles on top of you. From the shaky moan that escapes him, you know the tip of your length must have reached his heart, but the tank is full enough that you can't see it. Mettaton doesn't seem to know what to do with his hands, and they both tangle in his hair for a moment before he brings one down, biting softly on two of his fingertips.

"Oh fuck," he whispers. "F-f- _fuck_ , it feels even bigg-g-g-ger like this..."

His head falls back and he starts to move, haltingly slowly. You wonder how much more of it he's feeling, in this position, now that gravity's doing most of the work. Liquid starts to fill the tank with alarming speed, to the point that you can barely see the outline of his soul. When he gets a bit more used to it, he picks up speed, holding onto your arm for balance. The heat of his body makes the way the base moves against you all the sweeter.

"God, you look so hot," you hiss, your fingernails digging into his hips. 

"Really?" Mettaton looks at you with half-lidded eyes. "Is thissss-s a good look on me, s-sweetheart?"

"Fuck yes- _ngh!_ " You squeeze your eyes shut and grunt softly as he leans back a little. The angle works  _really_ well, and it looks like he noticed.

"Ooh, you like tttthat~" he gives your arm a gentle squeeze. "K-keep your eyes open? Pleas-s-se?"

"I'll try." It takes you a second, but you open your eyes, and now his heart tank is so full it's starting to drip down his front.

"Thank y-yyyyou," he gasps. "I lovvvve it when you watch me, when you see how-w-w-wwet I am for you..."

He swipes a finger through the liquid dripping out of him and licks it from his fingers. His hips grind against you, building up the heat between your legs until your breath is rough and heavy. You move with him in earnest, rolling your hips up to meet him as best you can.

"Oh yessss," he groans. "I'm so c-c-close, darling, I- _nnn_ , right there-!"

He throws his head back and cries out, and it sticks in a repeat loop before shorting out completely. He trembles on top of you, his hips shaking violently as liquid pours over your hips. The sight does you no favors, and it's all you can do not to throw him onto his back and relieve the pressure between your own legs. He's back to himself quicker than you expect, though, but confusingly the first thing he does is slide off you.

"Alright," he says, blinking a few times. "I think it's time I showed you." 

"...show me what." You say, feeling less and less amused.

"Your SOUL," he replies, sounding remarkably quiet. "If you want me to."

A moment of quiet passes between you, and you wonder if he's joking. From the looks of it, he's not.

"What do you mean?" you ask.

"Well, Alphys designed me to fight humans, back when...that was a thing I might need to do," he shakes his head. "It wouldn't hurt you. We've spent a long time making sure it wouldn't hurt you."

"I...oh my god," you take a moment to consider this. "Yes. Yes, I think...I want to at least try."

"Alright," he nods. "You should probably get comfortable, then." 

You shuffle out of the harness and lay down flat, feeling the warmth of his hands as they hover over you.

"If this hurts," he says, "if it feels wrong, if you want to stop for any reason at all...please, tell me."

"I will," you nod.

"Alright," he takes a deep breath, the pneumatic hiss clicking in your ears.

You can hear the sound of gears and motors moving inside his body, and magic begins to glow across his fingertips. His hand moves above your chest, and something... _moves_ inside you. From the soles of your feet, it draws up like thread being spooled together, pulling from the heat that still throbs between your legs, from your stomach and sides, from the tips of your fingers and the crooks of your elbows. It gathers under his hand, and it feels so strange your eyes slide close so you can try to process it. It feels warm, but sharp, the pull spreading up to your head, behind your eyes and lips, the points on your neck where your pulse bounds away, and it gathers just above your sternum. Just above your heart.

"Oh darling," he hums happily, "you're so beautiful."

You open your eyes, and the first thing you see is Mettaton's smiling face. His hand has moved a bit to the side, and hovering just above your chest is a heart, the same size as his, its surface faintly shimmering like a polished gem.

Despite yourself, you begin to laugh.

"What on earth is so funny?" Mettaton asks.

"I mean," you say, gesturing to your soul, "that's not my _favorite_ color, but it's pretty damn close."

Mettaton laughs softly, shaking his head.

"It looks very good on you," he murmurs, lifting his hand again. "I wonder...do you think I could try touching it?"

"I think you'd better," you say, without really thinking. "I mean-! I mean yeah. Yeah, you can touch it."

Mettaton laughs again, and slowly he traces a fingertip along the outer edge.

Despite the fact that you've seen firsthand what this does to him, you're completely unprepared. A current of pleasure hits you like a spark, clinging on and spreading gently through your body. You gasp and curl a little to one side, your eyes unfocused.

"Is this..." you pant, "Is this what you feel when I...?"

"God, I hope so," he purrs. "When you do it to me, it's _exquisite._ "

Before you can ask him to do it again, he drags his fingertips across its surface, and the current comes back. It spreads over you in crackling circuits, like a spider web branching out to nerves you didn't know you had. The noise you make is probably ridiculous. Your eyes close again, but you can feel what he's doing, his fingers moving up and down across the middle. Warmth floods you, and when he speaks again the sound sends shivers through your body.

"I want to taste you."

" _Yes_ ," you gasp, and his tongue is so hot, so wet and sweet and slow. You feel like a live wire, humming with so much energy you could burst.

The feeling fades, and you open your eyes to see him holding your heart in both hands. He looks down at you with such love in his eyes, it looks like he might cry.

"You taste so good," he whispers, and you feel it. "It's a different kind of good from the way your body tastes. I never thought...I never even _dreamed_..."

His lips press gently against your soul, and then his tongue returns. You moan breathlessly, your fingers grasping at the sheets. He laps at you, drinking you in, and it sends wave after wave of pleasure through your body. His fingers squeeze gently from behind, wrapping your body in warmth and sweetness, and it's too much. Your back snaps upwards, your hips following in a long, sinuous arch. You let it burn through you, your mouth open in an empty scream until you collapse, panting, onto the bed.

"Are you alright, darling?" he asks, softly petting your hair.

You just nod, not sure you can speak right now.

"Good."

After a bit, you open your eyes and smile at him. He leans down and kisses you gently, his hand rubbing soft circles over your shoulder.

"Do you think you have one more in you?" he says, and suddenly you've never wanted anything more.

"Yeah," you nod, already smiling in anticipation.

"I think maybe..." he sits up, and you hear the click of his heart container opening before you see it, "it's time we had a little heart-to-heart."

Your breath is shaky as it leaves you, which makes him smile. His tank clicks shut once his heart is out, keeping a good quantity of fluid inside. He slides his finger down the underside of your soul, and you're still shivering when he brings it up to his own. When his finger makes contact, his eyes go wide, and he curls forward with a gasp.

"I think..." he pants, "perhaps..."

He lies down on his side, and you follow, taking your own heart gently in your hand so you can bring it along. Mettaton brings a pink-coated fingertip to your heart, and after a moment of acknowledgement so you can see what he's doing, he touches it to the surface.

His reaction suddenly makes sense. His taste fills your mouth, and its sweetness flows through your whole body. The current that sparks over you runs deeper, layered with a rush of magic that's so distinctly _Mettaton_ , you wonder how it's possible for two people to be so close. You shiver and keen softly, feeling yourself curl inward. Before you can really think about what you're doing, you're moving closer to him, wrapping one arm around his shoulder and hooking your leg over his hip.

Your souls are less than an inch apart, and you can feel more of him, more of that magic hovering so promisingly close. His arm rests on your side, holding you steady.

"You want more?" He asks, sounding a little astonished. "Already?"

"Of course I do," you laugh a bit breathlessly. "I don't think I could ever get enough."

His smile is so bright, and the glow coming from his soul is even brighter. The warmth floods through you, and you move in closer just to feel more of it. Your souls are pressed together between you, and it's all you can do to curl your head into his neck and hang on. It feels like you're drowning in him, like you can feel him touching every inch of you, like your whole body is filled and surrounded by him. You're not sure which of you starts to move first, but your bodies roll together, sliding your hearts slowly over each other. Waves of pleasure move through you like a heartbeat, pulsing strong each time you move.

Every time he shivers or moans, you can feel his soul clench just a little. It hits you hard in a rush of magic, suffused with desire and joy. You've never been so unshakably certain that he wants this, he wants you. You wonder if he feels it from you too, but of course he does. Your pleasure flows back and forth, building off of each other until you're not so sure you're even two separate people, anymore.

He lifts your chin up and kisses you deeply, his lips still wet from your soul. He's right; you do taste good. It makes you happy in ways you've never imagined, knowing that this is what your soul is really like. Listening to the way he pants and whines against your lips, you feel indescribably light. He's feeling so good, and it's because of you - not even what you're doing to him, but you as a person. He _loves_ you, and even though you've never doubted that, it finally feels like you might be someone who deserves that kind of love.

Your soul begins to glow, and you're so happy you could die.

Mettaton tucks his face into your neck and whimpers, his whole body shaking harder and harder until he cries out against your skin. You grab hold of his hair and let out a breathless moan, feeling yourself shudder and spasm as your whole body lights up. It surges through you hard enough to make your eyes water, over and over and _over_ before it finally lets you go. When your body finally goes limp, you can barely breathe.

He lets go of you, and you collapse onto your back, chest heaving. Even then, you can hear his fans humming loudly in an effort to cool him down. Your eyes won't open, but you feel him gently push your soul back towards your chest, and it dissolves softly back into your body. You lie there for a while, just trying to catch your breath, not really thinking about moving, but after a bit you feel Mettaton's hand on your shoulder.

"Sit up for a moment," he says softly.

You do so, after a great effort. When you feel a cool glass of water against your lips, you drink it eagerly, and when it's empty you let yourself fall back onto the bed. You don't even feel Mettaton get up again before you're asleep.

You're not sure how long you're out, but when you wake up it's still dark outside. Even though you're under the covers now, you're still pretty cold without clothes on, so you roll over to see about finding your pajamas.

Mettaton has pulled the chair from his vanity over beside the bed, and from the looks of it he's been watching you the whole time. He's got his sketchbook out, drawing up a new costume design, or maybe something for the next MTT line, or...oh gosh, he wouldn't be drawing _you_ , would he? He notices you've moved and looks up, and the worry in his eyes makes you decide that maybe that's a question best left for another day.

"Are you feeling alright, darling?"

"M-hm," you nod, rubbing at your eyes. "Just cold."

"I thought that might happen," he helps you as you stumble out of bed.

You pull on your pajamas and flop back into bed, pulling Mettaton down to join you. He curls up next to you and kisses your forehead softly.

"I'm glad you're alright," he murmurs. "I was worried that may have been a bit...much."

"Don't apologize," you poke him in the arm. "That was amazing."

"I'm glad you enjoyed it," he runs one hand over your back. "I'm glad I could help you feel so good."

You blink for a moment, feeling just a little more lucid, and look right into his eyes. After everything that's happened this afternoon, you're not sure it even needs saying, but...

"I love you so much," you whisper, your voice just a little pinched. "I want to stay here. Like this. With you."

Under the covers, you can see Mettaton's soul begin to shine.

"I love you too," he takes your hand and kisses it gently, "and I'll stay with you as long as you'll have me."

You rest your head against the soft silicone of his shoulder and drift off to sleep, feeling so warm, so safe, so loved.


End file.
